Should President Trump end 'chain migration?'

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CLEARWATER, Minn. (AP) - Cardinals tuck into the dark wall of Norway spruce, finding shelter in the tall trees. Prickly, round seed balls dangle from a slender sycamore like tiny Christmas ornaments. A dawn redwood, native to China and found in fossil records dating back about 150 million years, drops flat rust-colored needles on the deep March snow.

When Steve and Jeanne Dirksen moved onto 40 acres outside Clearwater in the early 1970s, the yard was a cornfield and the 20-acre woods held a lot of oaks.

“There were two stunted little bur oaks in the middle of the field, in the middle of a rock pike,” Steve Dirksen said during a recent walk-through that was a bit like flipping through a field guide. He pointed to European horse chestnut, whose showy buds more than compensate for the large, prickly seed pods that follow. Firs, pines, ornamentals, berry producers, shade trees.

“At the time, I wasn’t trying to prepare myself for anything. On trips to Missouri and Iowa I would see trees that were absolutely gorgeous,” Dirksen told the St. Cloud Times (https://on.sctimes.com/1jyHlUc).

Many of the 40-plus planted species are strictly for enjoyment. But it turns out some of the seedlings collected from southern latitudes might be more likely to survive a warming climate.

A trained forester whose philosophy is tempered by his role as a volunteer Minnesota Master Naturalist, Dirksen takes a different approach with his 28-acre forest. There, he plants native species more likely to adapt because their natural range extends farther south.

“The biggest thing that we don’t know is what is natural. We only know what we see. It’s only been 10,000 years since the last glacier’s retreat. If nature can take care of itself without our help, I don’t see a reason why we have to help nature,” Dirksen said. “The other side of it is, I will help with nature for my own pleasure.”

Some scientists predict Minnesota in 100 years will look more like Kansas, with the dominant trees species becoming those that we’re more likely to see now in our river bottoms - things such as silver maples, willows, cottonwoods, hackberries.

The June 2012 Climate Central report “The Heat Is On: U.S. Temperature Trends” stated Minnesota’s climate has warmed about 0.23 of a degree per decade during the past 100 years. Since 1970, the rate has been 0.62 of a degree per decade - partly because the ‘70s were cooler than average, partly because the past 20 years have been warmer than the long-term average.

The Nature Conservancy’s Climate Wizard, which is based on weather-station data, found the biggest changes occurred in the form of increased precipitation and warmer winters.

“I think that people are a little bit overwhelmed by the enormity of climate change, and they don’t necessarily know how to tackle such a big question and how to prepare for it,” said Leslie Brandt, St. Paul-based climate specialist with the Northern Institute of Applied Climate Science.

Convincing people that climate change is real is one thing her colleague, Stephen Handler, a Houghton, Mich.-based climate change specialist with NIACS, does not do. Instead, he works with forest owners and land managers to put information into practice.

“What’s at risk and what can we do to start adapting and preparing?” Handler said. “That’s what we focus on.”

He usually starts by prompting landowners to ask some of the questions Dirksen already has answered.

“Figure out what’s important to you and what sort of values you want your woods to provide for the long term. Once you have a good picture of that, then there’s going to be some adaptation choices that will make sense for you. That’s not saying that it’s a guarantee.”

Someone who wants to preserve rare orchids that grow in a black-spruce peat bog, one of the most threatened Minnesota habitats, might take a defensive approach. Protecting the habitat for as long as possible might mean removing culverts - or even irrigating - to keep water levels up. It might mean intensive monitoring for forest pests. The approach is riskier in the long term because conditions are projected to worsen for that habitat.

Someone who wants to provide bird habitat or a timber harvest but doesn’t care exactly what shape that forest takes - Northern red oaks or black oaks from southern latitudes - might plant a mix of those species.

“This is one where we haven’t run into any landowners who are ready to go that far yet. I’m sure a lot of people are already planting a couple things in their backyard just to watch them,” Handler said.

Because scientists can’t predict how trees might adapt over the long term, no one is suggesting a complete overhaul of the landscape.

Yet Handler doesn’t buy the the idea that adaptation will keep pace with climate change this time. It’s happening faster. And human settlement has broken up the path species might otherwise take as they creep northward.

“Those forest species didn’t have to move across 100 miles of subdivisions and parking lots,” Handler said.

In his own 3-acre yard just outside Houghton, Handler has planted a few oaks and hickory from Iowa.

“I have to confess, I’m guilty of trying to plant a couple of southern tree species jut to try,” Handler said. “But I have no idea what this winter did to them.”

Brandt said most of the assisted migration has taken place on a small scale, in backyards.

Meanwhile, Handler finished out his plantings with a range of native species, including some projected losers such as hemlock. With Houghton’s milder, lake-effect climate, Handler said, someday that planting could be one of the last refuges.

“I think most people are at the point where they still want to focus on managing species that are currently native to their area, but they’re going to focus on those species that are also able to withstand changes in climate that are projected in the area,” Brandt said.

That’s what Dirksen did after oak wilt and Dutch elm disease took many of his trees in the 1970s. Today, his oak forest is turning into more of a big-woods mix with red maples and basswood, along with white oak, hackberry and black cherry.

Over the years, the Dirksens have planted about 7,000 trees. About 4,500 of them grow in a 5-acre plantation managed through the Conservation Stewardship Program.

Among the failures on that plot: the whole lot of 200 Ponderosa pines. Of the Douglas fir there, only one or two survived. (An ornamental Douglas fir thrives in the yard, where Dirksen babied it.)